A conventionally well-known transparent conductive film is so-called conductive glass which includes a glass substrate and an ITO film (indium-tin composite oxide film) formed thereon. On the other hand, the glass substrate has low flexibility and workability, and cannot be used in some applications. In recent years, therefore, transparent conductive films having an ITO film formed on various polymer film substrates such as polyethylene terephthalate films have been proposed because of their advantages such as excellent flexibility, workability, and impact resistance, as well as light weight.
Characteristics such as high transparency, high transmission, and high durability have been demanded for a transparent conductive material represented by a touch panel. During sputtering film deposition of a transparent thin film, sputtering performed so that the amount of atoms included in a sputtering gas in the thin film is 0.05 atomic % or less is known as a measure for improving transmittance (see Patent Document 1).
In addition, decreases in a specific resistance value and a surface resistance value are increasingly required for the ITO film formed on the polymer film substrate for high sensitivity (improvement in operability) and low power consumption in order to correspond to an increase in touch screen panel. A technique for forming an ITO film on a film substrate by means of a magnetron sputtering method setting a horizontal magnetic field on a target material to 50 mT or more has been proposed as a measure for providing a transparent conductive film having excellent light transparency and low specific resistance (see Patent Document 2).